When the Kenai and Kasilof Rivers Flowed Backward by Ted Bailey
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Refuge Notebook • Vol. 20, No. 11 • March 23, 2018 When the Kenai and Kasilof Rivers flowed backward by Ted Bailey Looking south over the outwash delta at the head of Tustumena Lake showing where water and sand erupted from the ground and fractured the ice 54 years ago. Photograph taken shortly after the March 27, 1964 earthquake byAve Thayer, Kenai National Moose Range. It must have been an alarming sight to see these tra (2004) were both 9.1 earthquakes. The Great two Kenai Peninsula rivers temporarily flow backward Alaskan Earthquake lasted four minutes and thirty- into the outlets of Kenai and Tustumena Lakes. But it eight seconds compared to the recent January 23, 2018 also had been a most disturbing day. earthquake off the coast of Kodiak, which seemed to That evening (5:36 PM) on Good Friday, March 27, last a long time, but lasted only about a minute and 1964 the great Alaskan Earthquake struck southcen- was registered at 7.9. The 1964 earthquake was a de- tral Alaska. It was the strongest earthquake (9.2 on structive subduction zone quake where two tectonic the Movement Magnitude Scale) measured in North plates converge. The 2018 Kodiak earthquake was a America and the second strongest in the world, sur- strike-slip quake, which is less destructive, caused by passed only by the 9.5 Valdivia earthquake off the coast horizontal motion across a fault. of Chile on May 22, 1960. Of the many distructive effects of the Great 1964 For comparison, the destructive earthquakes off Alaskan Earthquake, the temporary reversals of flow the east coast of Japan (2011) and west coast of Suma- of the Kenai River out of Kenai Lake and the Kasilof 22 USFWS Kenai National Wildlife Refuge Refuge Notebook • Vol. 20, No. 11 • March 23, 2018 River out of Tustumena Lake were relatively benign sures in the outwash delta at the head of the lake. Later from a human damage perspective. Reports later pub- in June the late Joe Magargl from Kasilof reported the lished by the U.S. Geological Survey attributed the level of Tustumena Lake was well below normal sea- temporarily change in the direction of flow to the tilt- sonal levels. By late autumn 1964, it was estimated to ing of the basins of Kenai and Tustumena Lakes, both be five feet below normal level. of which were frozen at the time. The tilting of the lake One effect of the earthquake on the Refuge’s fish basins, about three feet at Kenai Lake and a foot or less and wildlife occurred when the sloshing of water and at Tustumena Lake, caused the water in the lakes to ice back and forth in frozen lowland lakes destroyed slosh back and forth (seiching), temporarily reversing beaver lodges and bank dens or left them exposed the flow of the rivers at the mouths of both lakes. above the water line. Water levels in the Finger Lakes According to the above reports, several witnesses area dropped about five feet. Such abrupt changes un- saw the Kenai River reverse and flow back into the out- doubtedly affected resident fish populations. Faults let of Kenai Lake. One witness, John Ingram of Cooper and fissures occurred in the ground throughout the Landing, could see logs on the bottom of Kenai Lake Refuge. One such fissure can still be seen 54 years later and the Kenai River rapidly rushing back into Kenai on the trail to Silver Lake near the trailhead. Lake. The lake level was later estimated to have tem- porarily dropped 15 feet. Damage to trees along the A later (1993) radiocarbon study, which dated lay- shoreline from the sloshing water extended to about ers of buried organic material in the Kenai and Kasilof 30 feet above the lake level. River Flats, Chickaloon Bay and other similar sites in Flow in the Kasilof River was so low after the the Cook Inlet region, suggested that in the past 5,000 earthquake that it almost ran dry. The late Joe Sec- years there have been six to nine major subsistence ora, then living at the upper end of Tustumena Lake, events associated with major, probably great, earth- reported that the lake level rose and fell for about two quakes. This gives an average reoccurance interval of hours after the earthquake as the water sloshed back roughly 600 to 800 years between major earthquakes, and forth in the basin. The day following the earth- but this is only an average. Who knows for certain quake, a biologist from the Alaska Department of Fish when the next big earthquake may happen? and Game reported he was able to walk in its channel Dr. Ted Bailey, supervisory wildlife biologist at wearing only overshoes. Kenai National Wildlife Refuge before retiring in A photograph of upper Tustumena Lake taken a 2001, has lived on the Kenai Peninsula for over 40 couple of days later by Ave Thayer, Assistant Refuge years. Find more information about Kenai Refuge Manager and pilot of the then Kenai National Moose at http://kenai.fws.gov or http://www.facebook.com/ Range, shows where water and sand erupted out of fis- kenainationalwildliferefuge. USFWS Kenai National Wildlife Refuge 23.